1. Technical Field of the Invention
The present invention relates to a color filter substrate and a method of producing the same, a liquid crystal display panel using the color filter substrate, and an electronic apparatus.
2. Description of the Related Art
A liquid crystal display panel comprises a pair of substrates bonded together with a sealant, and liquid crystals sealed between both of the substrates. In order to define an alignment state of the liquid crystals when a voltage is not applied thereto, in general, the liquid crystal display panel is formed so that alignment films that are formed on the surfaces of the respective substrates opposing the liquid crystals using polyimide or the like are rubbed. The rubbing is an operation that is carried out on the surfaces of the alignment films in a certain direction with a rubbing cloth (buff cloth) wound upon a roller.
However, dust that is produced when the surfaces of the alignment films are rubbed with a rubbing cloth adheres to a display area, so that a reduction in the display quality, such as an uneven display, results. In addition, the surface states of the rubbed alignment films are determined by various conditions associated with rubbing, such as the strength or force with which the tip of the rubbing cloth contacts the surfaces of the alignment films, the material of the rubbing cloth, or how fast the alignment films are rubbed with the rubbing cloth. However, these conditions have many uncertainties, so that many of them are difficult to control qualitatively. For this reason, it becomes difficult to form alignment films of desired qualities, and therefore the yield of liquid crystal display panels is reduced. Further, when a liquid crystal display panel comprising a switching element such as a TFD (thin film diode) element or a TFT (thin film transistor) element is used, these switching elements may break due to static electricity that is produced when the alignment films are rubbed with a rubbing cloth. Accordingly, since various problems arise due to rubbing, there is a need for a technology for defining the state of alignment of liquid crystals without rubbing alignment films.
The present invention has been achieved in view of the above-described circumstances, and has as one object the provision of a color filter substrate which makes it possible to restrict the occurrence of problems caused by rubbing an alignment film, a method of producing the color filter substrate, a liquid crystal display panel using the color filter substrate, and an electronic apparatus.
To overcome the above-described problems, according to the present invention, there is provided a color filter substrate comprising one of a pair of substrates for sandwiching liquid crystals and color filters, the color filters are disposed on the surface of the one substrate that faces the liquid crystals, the color filters transmit light of a particular wavelength and have surface profiles defining a state of alignment of the liquid crystals.
With such a color filter substrate, since the surface profile of each color filter defines the state of alignment of the liquid crystals, it is not necessary to rub an alignment film for defining the state of alignment of the liquid crystals. Therefore, the occurrence of the various problems caused by rubbing an alignment film, such as the adherence of dust that is produced as the alignment film is rubbed or electrostatic damage to a switching element, is eliminated, so that a high yield of color filter substrates can be maintained.
The surface of each color filter may have a profile defined by a plurality of alignment control protrusions whose top portions extend in one direction. By using this structure, it is possible to align (in parallel) liquid crystal molecules to which a voltage is not applied so that the long axes thereof are disposed along the aforementioned one direction. Alternatively, the surface of each color filter may have a profile defined by an alignment control protrusion having a plurality of surfaces that are inclined with respect to the surface of the one substrate and protruding towards a side away from the one substrate at an intersection line of each surface. By using this structure, it is possible to align (vertically) liquid crystal molecules to which a voltage is not applied so that the long axes thereof face a direction perpendicular to the inclined surfaces. The surface of each color filter may have a curved profile protruding towards a side away from the one substrate to similarly achieve vertical alignment.
According to another aspect of the present invention, there is provided a liquid crystal display panel comprising liquid crystals between a pair of opposing substrates, and color filters which are disposed on the surface of one of the pair of substrates that faces the liquid crystals. The color filters transmit light of a particular wavelength and have surface profiles defining a state of alignment of the liquid crystals.
In this liquid crystal display panel, since the surface profile of each color filter can define the alignment state of the liquid crystals, as in the color filter substrate described above, the occurrence of the various problems caused by rubbing an alignment film can be eliminated. In the liquid crystal display panel, the surface of each color filter may have a profile defined by a plurality of alignment control protrusions whose top portions extend in one direction; or the surface of each color filter may have a profile defined by an alignment control protrusion having a plurality of surfaces that are inclined with respect to the surface of the one substrate and protrude towards a side away from the one substrate at an intersection line of each surface; or the surface of each color filter may have a curved profile protruding towards a side away from the one substrate. In other words, the surface profile of each color filter may be selected so that the long axes of the molecules of the liquid crystals are substantially parallel, that is, so that they are aligned in parallel (or homogeneously) with respect to the surface of one of the substrates, or so that the long axes of the liquid crystal molecules are inclined, that is, so that they are aligned vertically (or homeotropically) with respect to the surface of one of the substrates. The state of alignment of the liquid crystals is not limited to these, so that the liquid crystal molecules may be aligned in other ways. In other words, the surface profile of each color filter is not limited to the above-described profiles, so that the liquid crystal molecules can be aligned in other desired directions as appropriate.
According to another aspect of the present invention, there is provided an electronic apparatus comprising the above-described liquid crystal display panel. As mentioned above, according to the liquid crystal display panel of the present invention, it is possible to eliminate a reduction in the yield of color filter substrates, so that the cost of producing the electronic apparatus that incorporates the liquid crystal display panel can be reduced. Examples of such an electronic apparatus include a personal computer and a cellular phone.
According to another aspect of the present invention, there is provided a method of producing a color filter substrate including one of a pair of substrates for sandwiching liquid crystals and color filters which transmit light of a particular wavelength. The method comprises a first step of forming a resin layer on the surface of the one substrate that faces the liquid crystals, and a second step of selectively removing portions of the resin layer in order to form the color filters having surface profiles that define a direction of alignment of the liquid crystals.
According to this method, since color filters having surface profiles defining the direction of alignment of the liquid crystals are formed, it is not necessary to rub an alignment film. Therefore, it is possible to eliminate the occurrence of the various problems caused by the rubbing. In addition, since profiles for defining the direction of alignment of the liquid crystals are provided at the same time that the color filters are formed, the production process is simplified and production cost is reduced compared to the case where a member for defining the direction of alignment of the liquid crystals is formed separately from the color filter.
The second step may comprise removing a plurality of linear areas at a surface of the resin layer over a portion of the resin layer in the thickness direction thereof. Alternatively, the second step may comprise removing a portion of the resin layer with successively varying depths in accordance with locations of a surface of the resin layer. The portion of the resin layer that is removed is not limited to the aforementioned portions, so that a portion of the resin layer that is removed may be selected in accordance with the desired alignment state of the liquid crystal molecules as appropriate.